Radio receiving and transmitting apparatus



y 1934- 'r. A. MARSHALL 1,956,582

RADIO RECEIVING AND TRANSMITTING APPARATUS Filed Dec. 3, 1929 4Sheets-Sheet 1 AP 9 7H WI} hllhlllmm 43 I g 42 4/ Thomas A. Mars/1aINVENTOR ATTORNEY May 1, 1934. T. A. MARSHALL RADIO RECEIVING ANDTRANSMITTING APPARATUS Filed Dec. 5, 1929 4 Sheets-Sheet 2 Thomas A.Mars/2a INVENTOR CJ flaw ATTORN EY y 1934- 'r. A. MARSHALL ,5

RADIO RECEIVING AND TRANSMITTING APPARATUS Filed Dec. 3, 1929 4Sheets-Sheet 5 9 f b l3 4 f 8 m n M l- \i 7 H 18 Thomas A.Mar5/7al1 )5INVENTOR 3 A i We ATTORNEY l, 1934. 'r. A. MARSHALL 1956582 RADIORECEIVING AND TRANSMITTING APPARATUS Filed Dec. 3, 1929 4 Sheets-Sheet 4r a 6 F V 26 V )1 AL I6 I 15 A! I 6 Mg as F]: J T 18 I'll Thoma; A.Mam/1a?) 27 lNVENTOR BY fl|l|85ll|ill W W 2 22 ATTORNEY Paras FFE RADIORECEIVING AND TRANSMITTING APPARATUS Thomas Aibert Marshall, UnitedStates Navy Application December 3, 1929, Serial No. 411,318

16 Claims. (Cl. 179-171) (Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 O. G. 757) My invention relates broadly toradio receiving ordinary three element tubes are employed and andtransmitting circuits and more specifically a novel balance system isprovided. to a circuit arrangement for a push-pull, radio Figure 1comprises a push-pull radio frequency frequency amplifier as applied toreceiving and amplifier circuit in which 1 represents the antransmittingcircuits. tenna, and 2 and 3 the antemia coupling coils. GO 5 One of theobjects of my invention is to pro- The numeral 4. is a split condenserhaving its vide a system for receiving and transmitting radio two halvesin series and respectively connected signalling energy, in which thetotal effective tube to the grids or control electrodes 11 and 15 ofcapacity on the tuned input circuit is substanthe two tubes 7 and 8,through grid condensers tially lowered. 5 and 6. The center connectionof the split con- 10 Another object of my invention is to provide denseris connected to the filament or cathodes a circuit having a high degreeof symmetry, and 12 and 16 of the tubes '7 and 8, and may be thereforepeculiarly adapted to a variety of uses grounded as at 44 if desired. Itis seen that each as, for example, for use in connection with a digridto filament capacity is across one of the rectional loop. halves of thesplit condenser. The total effec- 70 Still another object of myinvention is to protive tube capacity is thus halved. It is to be vide aradio frequency amplifier circuit having noted that the two grids tofilament circuits are a relatively high L/C ratio. each across half ofthe tuned circuit input voltage A further object of my invention is toprovide which decreases the grid to filament energy disa push-pullcircuit in which there is no direct sipation to one quarter of theamount for a sin- 7 center connection to the coils in the grid circuit,gle tube across the full voltage.

these coils being permitted to find their own eleo- Using the splitcondenser gives an advantage trical center, which may be different fromthe apover the usual push-pull circuit in that no cenparent center dueto electrical irregularities in ter connection is need for the grid coil3. This the circuits and tubes. coil is permitted to find its ownelectrical center 86 Other and further objects of my invention willwhich may be diiierent from the apparent cenappear more fullyhereinafter as the descripter due to electrical irregularities in thecircuits tion of the method and apparatus is developed. and tubes. Thecircuit thus helps to preserve lT fy invention consists substantially inthe conthe electrical symmetry which is essential to efstruction,combination, and arrangement of parts ficient and stable operation andalso permits a 30 associated therewith or as will be more fully highratio WhiCh is particularly desirable at h i fte set forth as shown bythe accomhigher frequencies, as it results in the desired panyingdrawings and finally defined in the apfrequencies being spread overalarger range of l condenser settings, thus making the tunlng of pendedclaims.

to be to assassinstars; if. 90 drawings forming a part of thisspecification in which like characters indicate corresponding Waves fromSay one to thlrty metels long In the circuit shown in Figure 1 two highinparts throughout the several views and in \Vnl-1 ductance 10w capacltychokes 24 and 25 are com Flgure q a raldw frequgncy m nected to theplates 13 and 9 of the tubes 8 and 40 clrcmt mcludmg 9 condense? m '7respectively, and in series with each other. A the grid circuit inaccordance with my invention; third and similar choke 23 is connected t0the Figure 2 is an improveddetector Circuit junction of the two platechokes and in series bodyins the elements of my invention; with the Bbattery 22. This additional or third Figure 3 is a circuit with thecircuits of Figure choke Serves the purpose of isolating the jun tion451 and Figure 2 combined and a stage of audio of th t plate hokes fromthe ground potenfrequency amp fi tio added thereto; tial. This permitsof the chokes finding their Figure 4 ShOWS y invention p d to a radioown electrical center which may be different from compass circuit; theapparent center due to electrical irregularities Figure 5 shows myinvention adapted to a of the circuits and tubes. This, with thearrange- 'tra m tt circuit; ment in the input circuit, helps preserveelectri- Figure 6 is a modification of Figure 1 with a cal symmetry. Thebattery 21 regulated by recondenser shunting the coils in the platecirsistance 20 serves to heat the filaments 12 and cult; and 16. Gridleak resistances l7 and 18 are con- Figure 7 is a modification of Figure1 in which nected across the grids, their junction being connected tothe filaments through resistance 20. The screen grids, 10 and 14, areconnected to a suitable point on the B battery 22 and to the groundthrough condenser 19. The output is connected through condensers 26 and27 to the coil 29 of the detector circuit shown in Figure 2. a

In the circuit shown in Figure 2, the tuning condenser 30 is similar tothat employed in the amplifier circuit. The push-pull arrangement of thetwo detector tubes 36 and 37 again permits electrical symmetry and ahigh L/C ratio,

Coil 29 is connected to the grids 39 and 42 through grid condensers 31and '32. Grid leak resistances 33 and 34 are connected across the grids,their junction being connected to the filamerits 40 and 43 throughresistance 35.

The tickler feed-back inductance coil 28 is tapped in the center andconnected to the plus B battery 22 terminal through a radio frequencychoke 49, the head phones 50' and the variable resistance 46 which isshunted by condenser 4'7.

Battery 21 heats the filament.

Regeneration may be controlled by Varying the direct current voltage onthe plate elements 38 and 41 of the two detector tubes 36 and 37.

Figure 3 is a'combination of the circuits of Figures 1 and 2. Thedetector circuit and the radio frequency amplifier are in individualshielded compartments. The two are coupled by the two condensers 26 and27 which aresmall enough to prevent undesired reaction of the circuits.In this circuit a stage of audio frequency amplification is showncoupled through transformer 48. The numeral 51 is a tube having the grid53, the plate 52 and the filament 54 which is connected to the battery55 through the resistance 57. B battery 56 furnishes the plate voltage.

Figure 4 is diagram showing the push-pull amplifier adapted to a radiocompass coil. This is an improvement over the single tube stages due tothe perfect electrical symmetry obtained. In the single tube circuits,the most common cause for the destruction of the null point is due tothe antenna effect which is caused by the electrical dissymmetry of theradio compass circuit. If one side of the loop is connected to the grid,while the other side is connected to the filament which i is common toall the battery circuits, giving high ground capacity, an electricaldissymmetry exists on account of the unequal capacities to ground of thetwo loop connections. This unbalancing of the circuit permits the coilto function additionally as an antenna circuit. For this reason, whenthe a coil system is at right angles to the direction of the propagationof the electro-magnetic wave, there is an indirect current in thecircvut which is due to the coil as an antenna. The circuit in Figure 4,due to perfect electrical symmetry, eliminates all antenna efiects whichpermits a sharp point of silence to be obtained. In this circuit, 1 isthe coil antenna, 4, the split condenser connected through gridcondensers 5 and 6 to the grids 11 and 15 or the tubes '7 and 8respectively. Grid leak resistances l7 and 18 areconnected throughresistance 58 to the filaments l2 and .16. The battery 21, throughresistance 20, furnishes the filament current. The B battery 22 togetherwith the plates 9 and 13 form the intra-electrode capacity obtained inthe receiving circuit of course are present in this transmittin circuit.In this circuit the coil 63 which receives the input is connected to thegrids 72 and 75' of the tubes 69 and '76 through the grid condensers 65and 66 respectively. The split condenser 64 performs he same function ascondenser 4 does in Figure 1. The center electrode of condenser 64 maybe grounded as at 59 if desired. The filaments 73 and 76 are heated froman alternating current source 80, connected through transformer 79.shunted across the secondary of this transformer are two condensers 7'7and 78 connected in series. The mid-point of the secondary is connectedto a point between these two condensers and to the rotor of the splitcondenser 64. Two radio frequency chokes 67 and 68, connected in series,-are placed across the grids 72 and 75. The mid-point of the secondaryof transformer 79 is also connected to a point between these two chokes.The plates 71 and 74 of the tubes are connected through coupling coils82 and 33 to the antenna 84. The mid-point of coil 82 is connected tothe plus plate voltage source through radio frequency choke 81, thenegative of this source being connected to the mid-point of thetransformer 79. tuning condenser 86, with the ammeter 85 in seriestherewith, is shunted across the plate circuit.

Figure 6 shows a circuit identical with that shown in Figure 1 exceptthat the output plate circuit has been modified by the substitution ofthe circuit containing the capacity 61 and inductance 62, for the coils24 and 25 permitting a high plate load impedance, which gives greatersignal strength than the circuit shown in Figure 1.

Figure 7 is a circuit similar to Figure 1, except that three elementtubes are used instead of four element tubes. In this circuit balancingcondensers 59 and 60 are connected between plate 9 and grid 15, andplate 13 and grid 11 respectively. This criss-cross balancing condenserarrangement could also be used in Figure 1 if desired but is notnecessary.

It will be understood that the above description and accompanyingdrawings comprehend only the general and preferred embodiments of myinvention and that minor detail changes in the construction andarrangement of parts may be made within the scope of the appended claimswithout sacrificing any of the advantages of my invention.

The invention herein described may be manufactured and used by or forthe Government of the United States without the payment to me of anyroyalties thereon or therefor.

Having described my invention, what I claim is:

1. A signal circuit including a single coil and a condenser in parallelto form a tunable circuit, said condenser having more than two plates,one of the plates of the condenser being positioned at the mid-point ofthe potential gradient across said condenser, a pair of vacuum tubes,each having a cathode, anode, control electrode and screen gridelectrode, the cathodes of said tubes being connected to the plate whichis positioned atthe midpoint of the potential gradient, the controlelectrodes of said tubes being connected to other plates in saidcondenser, and a capacity connecting the cathodes of said tubes to thescreen grid electrodes of said tubes whereby said tuned circuit and thescreen grid electrodes of said tubes are maintained symmetrical withrespect to the cathodes of said tubes.

2. A signal circuit including a single coil anda condenser in parallelto form a tunable circuit, said condenser having more than two plates,one of the plates of the condenser being positioned at trodes, a circuitconnecting the cathodes of said necting each of said screen gridelectrodes through loop antenna, a tuning condenser having two themid-point of the potential gradient across said condenser, a pair ofvacuum tubes, each having a cathode, anode, and control electrode, thecathodes of said tubes being connected to the plate which is positionedat the mid-point of the potential gradient, the control electrodes ofsaid tubes being connected to the terminals of said coil, and aresistance connecting each control electrode to the cathode of saidtubes.

3. A signal circuit including a single coil and a condenser in parallelto form a tunable circuit, said condenser having more than two plates,one of the plates of the condenser being positioned at the mid-point ofthe potential gradient across said condenser, a pair of vacuum tubes,each having a cathode, and control electrode, the oathodes of said tubesbeing connected to the plate which is positioned at the mid-point'of thepotential gradient, the control electrodes of said tubes beingcapacitatively connected across said coil, and resistances of like valueconnecting the control electrode of each tube to the cathode of eachtube.

4. A signal circuit including a single coil and a condenser in parallelto form a tunable circuit, said condenser having more than two plates,one of the plates of the condenser being positioned at the mid-point ofthe potential gradient across said condenser, a pair of vacuum tubeseach having cathode, anode, control and screen grid electubes beingconnected to the condenser plate which is positioned at the midpoint ofthe potential gradient, connections between the control electrode andterminals of said coil, a circuit cona capacity to the last mentionedcondenser plate, and a balanced repeater circuit connected between theanodes of said tubes.

5. A radio receiving circuit comprising a single plates, one of which isconnected to one terminal of said loop, the other plate being connectedto the other terminal of said loop, means for balancing said loop withrespect to ground including an element located between said plates andconnected to ground, two thermionic repeater devices, each including ananode, cathode, and a control electrode, the control electrodes beingconnected to opposite plates of said tuning condenser and the cathodesbeing connected to ground and to the element located between the platesof said condenser, and a work circuit connected between said anodes.

6. In a balanced thermionic relay device, a pair of thermionic tubeseach having anode, cathode ture to the cathodes of said tubes, asymmetrical circuit including a source of potential connecting theanodes of said tubes to the cathodes of said tubes, and means forimpressing signal energy on said first named inductance.

7. A relay, as claimed in claim 6, in which the control electrode of onetube is capacitively coupled to the anode of another tube.

8. A thermionic translater including a plurality of thermionic tubeseach having anode cathode and control electrodes, means for impressingcscillations on said control electrodes comprising an inductance shuntedby a condenser having two sections formed by a common armature and twoisolated armatures, the common armature being connected to the cathodesof said tubes, the terminals of said inductance being connected to thecontrol electrodes of said tubes and to said isolated armatures, asymmetrical output circuit including an inductance and a parallelcondenser connected between the anodes of said tubes, a secondinductance connecting the midpoint of said last named inductance througha source of potential to the cathodes of said tubes, a utilizationcircuit comprising an inductance, a

circuit connecting each terminal of said inductance to the anode of oneof said tubes, and means for tuning said inductance and for balancingsaid utilization circuit with'respect to ground comprising, a condenserhaving two sections formed by a common armature and two insolatedarmatures, the common armature being connected to the cathodes of saidtubes, and the terminals of said last named inductance being connectedto the isolated armatures of said condenser.

99. Ultra high frequency relaying means comprising, a plurality of pairsof thermionic tubes, each tube having anode, cathode and control gridelectrodes, means for impressing oscillations to be relayed between thecontrol grid and cathodes of one of said pairs of tubes comprising, aninductance having one terminal connected to the control grid of one ofthe tubes of said pair and its other terminal connected to the controlgrid of the other tube of said pair, means for tuning said inductanceand balancing the same with respect to the cathodes of the tubes of saidpair comprising, a capacity connected in parallel with said inductance,an additional element in said capacity located between the terminalsthereof, a circuit connecting said additional element to the cathodes ofsaid tubes, a symmetrical output circuit connected between the anodes ofsaid pair of tubes, and means for coupling said output circuit to thecontrol grids of another pair of tubes comprising, an inductance, acapacitive connection between each terminal of said inductance and theanode of one of said tubes in said first named pair, a connectionbetween each terminal of said inductance and the control grid of a tubein said second named pair, and means for tuning said inductance andbalancing same with respect to the cathodes of the tubes in said secondnamed pair comprising, a capacity connected in parallel with saidinductance, and an additional element located between the terminals ofsaid capacity and connected with the cathodes of the tubes in saidsecond named pair.

10. A radio receiving circuit comprising a loop antenna including one ormore turns of conducting material, a tuning condenser having twoarmatures, one of which is connected to one terminal of said loop, theother armature being connected to the other terminal of said loop, meansfor balancing said loop with respect to ground including an elementlocated at the midpoint of the potential gradient between said aforesaidarmatures and connected to ground, a pair of thermionic repeaterdevices, each device including an anode, cathode, and a controlelectrode, a connection between the control electrode of one of saidtubes and one of said armatures of said tuning condenser, a connectionbetween the control electrode of the other of said tubes and the otherarmature of said tuning condenser, a connection between the cathodes ofeach of said tubes and groundand the element located between saidcondenser armatures, and means for connecting a work circuit. betweenthe anodes of said tubes.

11. In a thermionic relay device, a pair of thermionic tubes, eachhaving anode, cathode and control grids, and means for applyingpotentials to the control grids of said tubes comprising, an inductancehaving one terminal connected to the control grid of one of said tubesand the other terminal connected to the control grid of the other ofsaid tubes, and means for tuning said inductance to the frequency of thepotentials applied to the control grids and for balancing said circuitincluding said grids with respect to ground comprising, a capacityelement having two sections made up of a common armature cooperatingwith a pair of isolated armatures, one of said isolated armatures beingconnected to one terminal of said inductance, the other of said isolatedarmatures being connected to the other terminal of said inductance, saidcommon armature being connected to the cathodes of said tubes and toground, a load circuit connected with said anodes, and means forpreventing said load circuit and said anodes from reacting on saidcontrol grids and associated circuits including an auxiliary electrodeinterposed between the anode and control grid of each tube.

12. A device as recited in claim 11 in which' said load circuit iscapacitively coupled to said anodes.

13. A balanced amplifier circuit comprising a plurality of coactingamplification stages, each stage comprising a pair of electron tubes,said electron tubes comprising a cathode, a control grid, an anode and ascreen. grid, an input circuit for one pair of said tubes comprising aninductance, a tuning condenser having three plate systems, a connectionbetween one plate system and one end of said inductance, a connectionbetween another of said plate systems and the other end of saidinductance, said connections forming a closed tunable path, a pair ofcondenser units,

one of said condenser units being disposed in series between a controlgrid of one of said electron tubes and one end of said tunable path, aconnection between the control grid of the other of said electron tubesand the other end of said tunable path, a connection between the otherofsaid plate systems and said cathodes, a pair of separate resistorelements, said elements being connected in common at one end thereof, aconnection between the control grid of one of said electron tubes andone of said resistors, a connection between the control grid of theother of said electron tubes and the other of said resistors, meansconnecting the cathodes of said tubes with the common connection betweensaid resistors, a tuned circuit comprising an inductance shunted by acondenser, one end of said tuned circuit being connected with the anodeof one of said electron tubes and the other end of said tuned cir cuitbeing connected with the anodeof the other of said electron tubes, anelectrical connection between the screen grid electrodes of each of saidelectron tubes, and means for applying predetermined potentials to saidcathodes, said screen grid electrodes and to said anodes.

14. In a high frequency amplifier, a pair of electron tubes eachincluding a cathode, a control grid, an anode and a screen grid, acommon circuit for energizing said cathodes, a common connection betweensaid screen grids, a tunable circuit having one end connected with theanode of one electron tube and having the other end connected with theanode of the other of said electron tubes, a source of potentialconnected between said cathodes and a point in said tunable circuit, aconnection between said source of potential and the common circuitinterconnecting said screen grids, an inductance, a pair of independentcondensers, a connection between one end of said inductance through oneof said condensers to the control grid of one electron tube, aconnection from the other end of said inductance to the other of saidcondensers with the control grid of the other of said electron tubes, athree-electrode condenser system having one'electrode connected withsaid cathodes, one electrode connected with one end of said inductanceand the other electrode connected with the opposite end of saidinductance, a resistance unit connected between said control grids, atap intermediate the ends of said resistance unit, a variable resistorconnected with said cathodes, and a connection between said variableresistor and the tap on said resistance unit.

15. An ultrahigh frequency amplifier system comprising a pair ofbalanced electron tubes, each including a cathode, a control grid, ascreen grid and an anode, a tuned circuit interconnecting said controlgrids, a tuned output circuit connected with said anodes, a potentialsource for energizing said cathodes, and said anodes, a conductorinterconnecting said screen grid electrodes, a connection between saidconductor and said source of potential, and a condenser connectedbetween a midpoint along said conductor and said cathodes.

6. An ultrahigh frequency amplifier system comprising a pair of balancedelectron tubes, each including a cathode, a control grid, a screen gridand an anode, a tuned circuit interconnecting said control grids, atuned output circuit connected with said anodes, a potential, source forenergizing said cathodes and said anodes, a conductor interconnectingsaid screen grid electrodes, a connection between said conductor andsaid source of potential, and a large capacity condenser forming a lowimpedance path to ultrahigh frequency currents symmetrically connectedbetween said conductor and said cathodes.

THOMAS ALBERT MARSHALL.

